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802b0ea7 | 1 | @c This is part of the Emacs manual. |
b65d8176 | 2 | @c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2000, 2001, |
4e6835db | 3 | @c 2002, 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc. |
6bf7aab6 DL |
4 | @c See file emacs.texi for copying conditions. |
5 | @node Display, Search, Registers, Top | |
6 | @chapter Controlling the Display | |
7 | ||
8 | Since only part of a large buffer fits in the window, Emacs tries to | |
43d67313 RS |
9 | show a part that is likely to be interesting. Display-control |
10 | commands allow you to specify which part of the text you want to see, | |
11 | and how to display it. Many variables also affect the details of | |
12 | redisplay. Unless otherwise stated, the variables described in this | |
13 | chapter have their effect by customizing redisplay itself; therefore, | |
14 | their values only make a difference at the time of redisplay. | |
6bf7aab6 DL |
15 | |
16 | @menu | |
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17 | * Scrolling:: Commands to move text up and down in a window. |
18 | * Auto Scrolling:: Redisplay scrolls text automatically when needed. | |
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19 | * Horizontal Scrolling:: Moving text left and right in a window. |
20 | * Follow Mode:: Follow mode lets two windows scroll as one. | |
b8f3a9e3 | 21 | * Faces:: How to change the display style using faces. |
43d08eb9 | 22 | * Standard Faces:: Emacs' predefined faces. |
b8f3a9e3 | 23 | * Font Lock:: Minor mode for syntactic highlighting using faces. |
b8f3a9e3 | 24 | * Highlight Interactively:: Tell Emacs what text to highlight. |
fad78d58 | 25 | * Fringes:: Enabling or disabling window fringes. |
9d2908a6 | 26 | * Displaying Boundaries:: Displaying top and bottom of the buffer. |
fad78d58 | 27 | * Useless Whitespace:: Showing possibly-spurious trailing whitespace. |
6bf7aab6 DL |
28 | * Selective Display:: Hiding lines with lots of indentation. |
29 | * Optional Mode Line:: Optional mode line display features. | |
30 | * Text Display:: How text characters are normally displayed. | |
099bfef9 | 31 | * Cursor Display:: Features for displaying the cursor. |
9d2908a6 RS |
32 | * Line Truncation:: Truncating lines to fit the screen width instead |
33 | of continuing them to multiple screen lines. | |
0015d677 | 34 | * Display Custom:: Information on variables for customizing display. |
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35 | @end menu |
36 | ||
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37 | @node Scrolling |
38 | @section Scrolling | |
39 | ||
40 | If a buffer contains text that is too large to fit entirely within a | |
41 | window that is displaying the buffer, Emacs shows a contiguous portion of | |
42 | the text. The portion shown always contains point. | |
43 | ||
44 | @cindex scrolling | |
45 | @dfn{Scrolling} means moving text up or down in the window so that | |
46 | different parts of the text are visible. Scrolling ``forward'' or | |
47 | ``up'' means that text moves up, and new text appears at the bottom. | |
48 | Scrolling ``backward'' or ``down'' moves text down, and new text | |
49 | appears at the top. | |
50 | ||
51 | Scrolling happens automatically if you move point past the bottom or | |
52 | top of the window. You can also scroll explicitly with the commands | |
53 | in this section. | |
54 | ||
55 | @table @kbd | |
56 | @item C-l | |
57 | Clear screen and redisplay, scrolling the selected window to center | |
58 | point vertically within it (@code{recenter}). | |
59 | @item C-v | |
60 | Scroll forward (a windowful or a specified number of lines) (@code{scroll-up}). | |
61 | @item @key{NEXT} | |
62 | @itemx @key{PAGEDOWN} | |
63 | Likewise, scroll forward. | |
64 | @item M-v | |
65 | Scroll backward (@code{scroll-down}). | |
66 | @item @key{PRIOR} | |
67 | @itemx @key{PAGEUP} | |
68 | Likewise, scroll backward. | |
69 | @item @var{arg} C-l | |
70 | Scroll so point is on line @var{arg} (@code{recenter}). | |
71 | @item C-M-l | |
72 | Scroll heuristically to bring useful information onto the screen | |
73 | (@code{reposition-window}). | |
74 | @end table | |
75 | ||
76 | @kindex C-l | |
77 | @findex recenter | |
78 | The most basic scrolling command is @kbd{C-l} (@code{recenter}) with | |
79 | no argument. It scrolls the selected window so that point is halfway | |
80 | down from the top of the window. On a text terminal, it also clears | |
81 | the screen and redisplays all windows. That is useful in case the | |
82 | screen is garbled (@pxref{Screen Garbled}). | |
83 | ||
84 | @kindex C-v | |
85 | @kindex M-v | |
86 | @kindex NEXT | |
87 | @kindex PRIOR | |
88 | @kindex PAGEDOWN | |
89 | @kindex PAGEUP | |
90 | @findex scroll-up | |
91 | @findex scroll-down | |
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92 | To read the buffer a windowful at a time, use @kbd{C-v} |
93 | (@code{scroll-up}) with no argument. This scrolls forward by nearly | |
94 | the whole window height. The effect is to take the two lines at the | |
95 | bottom of the window and put them at the top, followed by nearly a | |
96 | whole windowful of lines that were not previously visible. If point | |
97 | was in the text that scrolled off the top, it ends up at the new top | |
98 | of the window. | |
99 | ||
43d67313 | 100 | @vindex next-screen-context-lines |
dc917bd9 | 101 | @kbd{M-v} (@code{scroll-down}) with no argument scrolls backward in |
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102 | a similar way, also with overlap. The number of lines of overlap that |
103 | the @kbd{C-v} or @kbd{M-v} commands leave is controlled by the | |
104 | variable @code{next-screen-context-lines}; by default, it is 2. The | |
105 | function keys @key{NEXT} and @key{PRIOR}, or @key{PAGEDOWN} and | |
106 | @key{PAGEUP}, are equivalent to @kbd{C-v} and @kbd{M-v}. | |
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107 | |
108 | The commands @kbd{C-v} and @kbd{M-v} with a numeric argument scroll | |
109 | the text in the selected window up or down a few lines. @kbd{C-v} | |
110 | with an argument moves the text and point up, together, that many | |
111 | lines; it brings the same number of new lines into view at the bottom | |
112 | of the window. @kbd{M-v} with numeric argument scrolls the text | |
113 | downward, bringing that many new lines into view at the top of the | |
114 | window. @kbd{C-v} with a negative argument is like @kbd{M-v} and vice | |
115 | versa. | |
116 | ||
117 | The names of scroll commands are based on the direction that the | |
118 | text moves in the window. Thus, the command to scroll forward is | |
119 | called @code{scroll-up} because it moves the text upward on the | |
120 | screen. The keys @key{PAGEDOWN} and @key{PAGEUP} derive their names | |
121 | and customary meanings from a different convention that developed | |
122 | elsewhere; hence the strange result that @key{PAGEDOWN} runs | |
123 | @code{scroll-up}. | |
124 | ||
125 | @vindex scroll-preserve-screen-position | |
126 | Some users like the full-screen scroll commands to keep point at the | |
127 | same screen line. To enable this behavior, set the variable | |
128 | @code{scroll-preserve-screen-position} to a non-@code{nil} value. In | |
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129 | this mode, when these commands would scroll the text around point off |
130 | the screen, or within @code{scroll-margin} lines of the edge, they | |
131 | moves point to keep the same vertical position within the window. | |
132 | This mode is convenient for browsing through a file by scrolling by | |
133 | screenfuls; if you come back to the screen where you started, point | |
134 | goes back to the line where it started. However, this mode is | |
135 | inconvenient when you move to the next screen in order to move point | |
136 | to the text there. | |
dc917bd9 RS |
137 | |
138 | Another way to do scrolling is with @kbd{C-l} with a numeric argument. | |
139 | @kbd{C-l} does not clear the screen when given an argument; it only scrolls | |
140 | the selected window. With a positive argument @var{n}, it repositions text | |
141 | to put point @var{n} lines down from the top. An argument of zero puts | |
142 | point on the very top line. Point does not move with respect to the text; | |
143 | rather, the text and point move rigidly on the screen. @kbd{C-l} with a | |
144 | negative argument puts point that many lines from the bottom of the window. | |
145 | For example, @kbd{C-u - 1 C-l} puts point on the bottom line, and @kbd{C-u | |
146 | - 5 C-l} puts it five lines from the bottom. @kbd{C-u C-l} scrolls to put | |
147 | point at the center (vertically) of the selected window. | |
148 | ||
149 | @kindex C-M-l | |
150 | @findex reposition-window | |
151 | The @kbd{C-M-l} command (@code{reposition-window}) scrolls the current | |
152 | window heuristically in a way designed to get useful information onto | |
153 | the screen. For example, in a Lisp file, this command tries to get the | |
154 | entire current defun onto the screen if possible. | |
155 | ||
43d67313 RS |
156 | @node Auto Scrolling |
157 | @section Automatic Scrolling | |
158 | ||
dc917bd9 | 159 | @vindex scroll-conservatively |
43d67313 RS |
160 | Redisplay scrolls the buffer automatically when point moves out of |
161 | the visible portion of the text. The purpose of automatic scrolling | |
162 | is to make point visible, but you can customize many aspects of how | |
163 | this is done. | |
164 | ||
165 | Normally, automatic scrolling centers point vertically within the | |
166 | window. However, if you set @code{scroll-conservatively} to a small | |
167 | number @var{n}, then if you move point just a little off the | |
168 | screen---less than @var{n} lines---then Emacs scrolls the text just | |
169 | far enough to bring point back on screen. By default, | |
9705fb37 | 170 | @code{scroll-conservatively} is@tie{}0. |
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171 | |
172 | @cindex aggressive scrolling | |
173 | @vindex scroll-up-aggressively | |
174 | @vindex scroll-down-aggressively | |
175 | When the window does scroll by a longer distance, you can control | |
176 | how aggressively it scrolls, by setting the variables | |
177 | @code{scroll-up-aggressively} and @code{scroll-down-aggressively}. | |
178 | The value of @code{scroll-up-aggressively} should be either | |
179 | @code{nil}, or a fraction @var{f} between 0 and 1. A fraction | |
180 | specifies where on the screen to put point when scrolling upward. | |
181 | More precisely, when a window scrolls up because point is above the | |
182 | window start, the new start position is chosen to put point @var{f} | |
183 | part of the window height from the top. The larger @var{f}, the more | |
184 | aggressive the scrolling. | |
185 | ||
186 | @code{nil}, which is the default, scrolls to put point at the center. | |
187 | So it is equivalent to .5. | |
188 | ||
189 | Likewise, @code{scroll-down-aggressively} is used for scrolling | |
190 | down. The value, @var{f}, specifies how far point should be placed | |
191 | from the bottom of the window; thus, as with | |
192 | @code{scroll-up-aggressively}, a larger value is more aggressive. | |
193 | ||
194 | @vindex scroll-margin | |
195 | The variable @code{scroll-margin} restricts how close point can come | |
196 | to the top or bottom of a window. Its value is a number of screen | |
197 | lines; if point comes within that many lines of the top or bottom of the | |
198 | window, Emacs recenters the window. By default, @code{scroll-margin} is | |
199 | 0. | |
200 | ||
201 | @node Horizontal Scrolling | |
202 | @section Horizontal Scrolling | |
203 | @cindex horizontal scrolling | |
204 | ||
205 | @dfn{Horizontal scrolling} means shifting all the lines sideways | |
206 | within a window---so that some of the text near the left margin is not | |
207 | displayed at all. When the text in a window is scrolled horizontally, | |
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208 | text lines are truncated rather than continued (@pxref{Line |
209 | Truncation}). Whenever a window shows truncated lines, Emacs | |
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210 | automatically updates its horizontal scrolling whenever point moves |
211 | off the left or right edge of the screen. You can also use these | |
212 | commands to do explicit horizontal scrolling. | |
213 | ||
214 | @table @kbd | |
215 | @item C-x < | |
216 | Scroll text in current window to the left (@code{scroll-left}). | |
217 | @item C-x > | |
218 | Scroll to the right (@code{scroll-right}). | |
219 | @end table | |
220 | ||
221 | @kindex C-x < | |
222 | @kindex C-x > | |
223 | @findex scroll-left | |
224 | @findex scroll-right | |
225 | The command @kbd{C-x <} (@code{scroll-left}) scrolls the selected | |
226 | window to the left by @var{n} columns with argument @var{n}. This moves | |
227 | part of the beginning of each line off the left edge of the window. | |
228 | With no argument, it scrolls by almost the full width of the window (two | |
229 | columns less, to be precise). | |
230 | ||
231 | @kbd{C-x >} (@code{scroll-right}) scrolls similarly to the right. The | |
232 | window cannot be scrolled any farther to the right once it is displayed | |
233 | normally (with each line starting at the window's left margin); | |
234 | attempting to do so has no effect. This means that you don't have to | |
235 | calculate the argument precisely for @w{@kbd{C-x >}}; any sufficiently large | |
236 | argument will restore the normal display. | |
237 | ||
238 | If you use those commands to scroll a window horizontally, that sets | |
239 | a lower bound for automatic horizontal scrolling. Automatic scrolling | |
240 | will continue to scroll the window, but never farther to the right | |
241 | than the amount you previously set by @code{scroll-left}. | |
242 | ||
243 | @vindex hscroll-margin | |
244 | The value of the variable @code{hscroll-margin} controls how close | |
245 | to the window's edges point is allowed to get before the window will | |
246 | be automatically scrolled. It is measured in columns. If the value | |
247 | is 5, then moving point within 5 columns of the edge causes horizontal | |
248 | scrolling away from that edge. | |
249 | ||
250 | @vindex hscroll-step | |
251 | The variable @code{hscroll-step} determines how many columns to | |
252 | scroll the window when point gets too close to the edge. If it's | |
253 | zero, horizontal scrolling centers point horizontally within the | |
254 | window. If it's a positive integer, it specifies the number of | |
255 | columns to scroll by. If it's a floating-point number, it specifies | |
256 | the fraction of the window's width to scroll by. The default is zero. | |
257 | ||
258 | @vindex auto-hscroll-mode | |
259 | To disable automatic horizontal scrolling, set the variable | |
260 | @code{auto-hscroll-mode} to @code{nil}. | |
261 | ||
262 | @node Follow Mode | |
263 | @section Follow Mode | |
264 | @cindex Follow mode | |
265 | @cindex mode, Follow | |
266 | @findex follow-mode | |
267 | @cindex windows, synchronizing | |
268 | @cindex synchronizing windows | |
269 | ||
270 | @dfn{Follow mode} is a minor mode that makes two windows, both | |
271 | showing the same buffer, scroll as a single tall ``virtual window.'' | |
272 | To use Follow mode, go to a frame with just one window, split it into | |
273 | two side-by-side windows using @kbd{C-x 3}, and then type @kbd{M-x | |
274 | follow-mode}. From then on, you can edit the buffer in either of the | |
275 | two windows, or scroll either one; the other window follows it. | |
276 | ||
277 | In Follow mode, if you move point outside the portion visible in one | |
278 | window and into the portion visible in the other window, that selects | |
279 | the other window---again, treating the two as if they were parts of | |
280 | one large window. | |
281 | ||
282 | To turn off Follow mode, type @kbd{M-x follow-mode} a second time. | |
283 | ||
b8f3a9e3 GM |
284 | @node Faces |
285 | @section Using Multiple Typefaces | |
286 | @cindex faces | |
287 | ||
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288 | You can specify various styles for displaying text using |
289 | @dfn{faces}. Each face can specify various @dfn{face attributes}, | |
290 | such as the font family, the height, weight and slant of the | |
291 | characters, the foreground and background color, and underlining or | |
292 | overlining. A face does not have to specify all of these attributes; | |
293 | often it inherits most of them from another face. | |
306da12e | 294 | |
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295 | On graphical display, all the Emacs face attributes are meaningful. |
296 | On a text-only terminal, only some of them work. Some text-only | |
306da12e | 297 | terminals support inverse video, bold, and underline attributes; some |
54952612 | 298 | support colors. Text-only terminals generally do not support changing |
306da12e | 299 | the height and width or the font family. |
c1b45553 | 300 | |
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301 | Emacs uses faces automatically for highlighting, through the work of |
302 | Font Lock mode. @xref{Font Lock}, for more information about Font | |
303 | Lock mode and syntactic highlighting. You can print out the buffer | |
304 | with the highlighting that appears on your screen using the command | |
43d08eb9 RS |
305 | @code{ps-print-buffer-with-faces}. @xref{PostScript}. |
306 | ||
0073fd65 RS |
307 | You control the appearance of a part of the text in the buffer by |
308 | specifying the face or faces to use for it. The style of display used | |
309 | for any given character is determined by combining the attributes of | |
310 | all the applicable faces specified for that character. Any attribute | |
0ec1f115 | 311 | that isn't specified by these faces is taken from the @code{default} face, |
04d0b662 | 312 | whose attributes reflect the default settings of the frame itself. |
b8f3a9e3 GM |
313 | |
314 | Enriched mode, the mode for editing formatted text, includes several | |
0073fd65 RS |
315 | commands and menus for specifying faces for text in the buffer. |
316 | @xref{Format Faces}, for how to specify the font for text in the | |
317 | buffer. @xref{Format Colors}, for how to specify the foreground and | |
318 | background color. | |
b8f3a9e3 GM |
319 | |
320 | @cindex face colors, setting | |
321 | @findex set-face-foreground | |
322 | @findex set-face-background | |
0073fd65 RS |
323 | To alter the appearance of a face, use the customization buffer. |
324 | @xref{Face Customization}. You can also use X resources to specify | |
186e9bcc | 325 | attributes of particular faces (@pxref{Resources}). Alternatively, |
0073fd65 RS |
326 | you can change the foreground and background colors of a specific face |
327 | with @kbd{M-x set-face-foreground} and @kbd{M-x set-face-background}. | |
328 | These commands prompt in the minibuffer for a face name and a color | |
329 | name, with completion, and then set that face to use the specified | |
3ae02d92 EZ |
330 | color. Changing the colors of the @code{default} face also changes |
331 | the foreground and background colors on all frames, both existing and | |
332 | those to be created in the future. (You can also set foreground and | |
333 | background colors for the current frame only; see @ref{Frame | |
334 | Parameters}.) | |
0073fd65 | 335 | |
1b35090d RS |
336 | Emacs can correctly display variable-width fonts, but Emacs commands |
337 | that calculate width and indentation do not know how to calculate | |
338 | variable widths. This can sometimes lead to incorrect results when | |
339 | you use variable-width fonts. In particular, indentation commands can | |
340 | give inconsistent results, so we recommend you avoid variable-width | |
341 | fonts for editing program source code. Filling will sometimes make | |
342 | lines too long or too short. We plan to address these issues in | |
343 | future Emacs versions. | |
b8f3a9e3 | 344 | |
43d08eb9 RS |
345 | @node Standard Faces |
346 | @section Standard Faces | |
347 | ||
b8f3a9e3 | 348 | @findex list-faces-display |
43d08eb9 RS |
349 | To see what faces are currently defined, and what they look like, |
350 | type @kbd{M-x list-faces-display}. It's possible for a given face to | |
351 | look different in different frames; this command shows the appearance | |
3b91a16d JL |
352 | in the frame in which you type it. |
353 | ||
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354 | Here are the standard faces for specifying text appearance. You can |
355 | apply them to specific text when you want the effects they produce. | |
b8f3a9e3 GM |
356 | |
357 | @table @code | |
358 | @item default | |
54952612 | 359 | This face is used for ordinary text that doesn't specify any face. |
43d08eb9 RS |
360 | @item bold |
361 | This face uses a bold variant of the default font, if it has one. | |
3b91a16d JL |
362 | It's up to you to choose a default font that has a bold variant, |
363 | if you want to use one. | |
43d08eb9 RS |
364 | @item italic |
365 | This face uses an italic variant of the default font, if it has one. | |
366 | @item bold-italic | |
367 | This face uses a bold italic variant of the default font, if it has one. | |
368 | @item underline | |
369 | This face underlines text. | |
370 | @item fixed-pitch | |
3b91a16d | 371 | This face forces use of a particular fixed-width font. |
43d08eb9 | 372 | @item variable-pitch |
3b91a16d | 373 | This face forces use of a particular variable-width font. It's |
54952612 | 374 | reasonable to customize this face to use a different variable-width font, |
3b91a16d JL |
375 | if you like, but you should not make it a fixed-width font. |
376 | @item shadow | |
377 | This face is used for making the text less noticeable than the surrounding | |
378 | ordinary text. Usually this can be achieved by using shades of gray in | |
379 | contrast with either black or white default foreground color. | |
43d08eb9 RS |
380 | @end table |
381 | ||
382 | Here's an incomplete list of faces used to highlight parts of the | |
383 | text temporarily for specific purposes. (Many other modes define | |
384 | their own faces for this purpose.) | |
385 | ||
386 | @table @code | |
387 | @item highlight | |
388 | This face is used for highlighting portions of text, in various modes. | |
389 | For example, mouse-sensitive text is highlighted using this face. | |
43d08eb9 | 390 | @item isearch |
54952612 RS |
391 | This face is used for highlighting the current Isearch match. |
392 | @item query-replace | |
393 | This face is used for highlighting the current Query Replace match. | |
43d08eb9 RS |
394 | @item lazy-highlight |
395 | This face is used for lazy highlighting of Isearch and Query Replace | |
396 | matches other than the current one. | |
397 | @item region | |
398 | This face is used for displaying a selected region (when Transient Mark | |
399 | mode is enabled---see below). | |
400 | @item secondary-selection | |
401 | This face is used for displaying a secondary X selection (@pxref{Secondary | |
402 | Selection}). | |
403 | @item trailing-whitespace | |
3b91a16d JL |
404 | The face for highlighting excess spaces and tabs at the end of a line |
405 | when @code{show-trailing-whitespace} is non-@code{nil}; see | |
406 | @ref{Useless Whitespace}. | |
43d08eb9 | 407 | @item nobreak-space |
5a7f4c1b | 408 | The face for displaying the character ``nobreak space.'' |
43d08eb9 RS |
409 | @item escape-glyph |
410 | The face for highlighting the @samp{\} or @samp{^} that indicates | |
411 | a control character. It's also used when @samp{\} indicates a | |
412 | nobreak space or nobreak (soft) hyphen. | |
43d08eb9 RS |
413 | @end table |
414 | ||
415 | @cindex @code{region} face | |
416 | When Transient Mark mode is enabled, the text of the region is | |
417 | highlighted when the mark is active. This uses the face named | |
418 | @code{region}; you can control the style of highlighting by changing the | |
419 | style of this face (@pxref{Face Customization}). @xref{Transient Mark}, | |
420 | for more information about Transient Mark mode and activation and | |
421 | deactivation of the mark. | |
422 | ||
423 | These faces control the appearance of parts of the Emacs frame. | |
424 | They exist as faces to provide a consistent way to customize the | |
425 | appearance of these parts of the frame. | |
426 | ||
427 | @table @code | |
b8f3a9e3 | 428 | @item mode-line |
3b91a16d JL |
429 | @itemx modeline |
430 | This face is used for the mode line of the currently selected window, | |
431 | and for menu bars when toolkit menus are not used. By default, it's | |
54952612 | 432 | drawn with shadows for a ``raised'' effect on graphical displays, and |
3b91a16d JL |
433 | drawn as the inverse of the default face on non-windowed terminals. |
434 | @code{modeline} is an alias for the @code{mode-line} face, for | |
435 | compatibility with old Emacs versions. | |
b9e58bf2 EZ |
436 | @item mode-line-inactive |
437 | Like @code{mode-line}, but used for mode lines of the windows other | |
438 | than the selected one (if @code{mode-line-in-non-selected-windows} is | |
ac6875fc RS |
439 | non-@code{nil}). This face inherits from @code{mode-line}, so changes |
440 | in that face affect mode lines in all windows. | |
d545c9fd JL |
441 | @item mode-line-highlight |
442 | Like @code{highlight}, but used for portions of text on mode lines. | |
443 | @item mode-line-buffer-id | |
444 | This face is used for buffer identification parts in the mode line. | |
b8f3a9e3 | 445 | @item header-line |
54952612 RS |
446 | Similar to @code{mode-line} for a window's header line, which appears |
447 | at the top of a window just as the mode line appears at the bottom. | |
448 | Most windows do not have a header line---only some special modes, such | |
449 | Info mode, create one. | |
53abc3bf | 450 | @item vertical-border |
58f1b4d8 JL |
451 | This face is used for the vertical divider between windows. |
452 | By default this face inherits from the @code{mode-line-inactive} face | |
54952612 | 453 | on character terminals. On graphical displays the foreground color of |
58f1b4d8 JL |
454 | this face is used for the vertical line between windows without |
455 | scrollbars. | |
3094ad7a | 456 | @item minibuffer-prompt |
3b91a16d JL |
457 | @cindex @code{minibuffer-prompt} face |
458 | @vindex minibuffer-prompt-properties | |
3094ad7a | 459 | This face is used for the prompt strings displayed in the minibuffer. |
3b91a16d JL |
460 | By default, Emacs automatically adds this face to the value of |
461 | @code{minibuffer-prompt-properties}, which is a list of text | |
43d67313 RS |
462 | properties used to display the prompt text. (This variable takes |
463 | effect when you enter the minibuffer.) | |
b8f3a9e3 | 464 | @item fringe |
3b91a16d | 465 | @cindex @code{fringe} face |
b8f3a9e3 GM |
466 | The face for the fringes to the left and right of windows on graphic |
467 | displays. (The fringes are the narrow portions of the Emacs frame | |
940627fe | 468 | between the text area and the window's right and left borders.) |
43d08eb9 | 469 | @xref{Fringes}. |
b8f3a9e3 GM |
470 | @item scroll-bar |
471 | This face determines the visual appearance of the scroll bar. | |
43d08eb9 | 472 | @xref{Scroll Bars}. |
b8f3a9e3 GM |
473 | @item border |
474 | This face determines the color of the frame border. | |
475 | @item cursor | |
476 | This face determines the color of the cursor. | |
477 | @item mouse | |
478 | This face determines the color of the mouse pointer. | |
479 | @item tool-bar | |
54952612 | 480 | This face determines the color of tool bar icons. @xref{Tool Bars}. |
b8f3a9e3 | 481 | @item tooltip |
43d08eb9 | 482 | This face is used for tooltips. @xref{Tooltips}. |
b8f3a9e3 | 483 | @item menu |
9e6bb19f EZ |
484 | @cindex menu bar appearance |
485 | @cindex @code{menu} face, no effect if customized | |
486 | @cindex customization of @code{menu} face | |
487 | This face determines the colors and font of Emacs's menus. @xref{Menu | |
488 | Bars}. Setting the font of LessTif/Motif menus is currently not | |
489 | supported; attempts to set the font are ignored in this case. | |
490 | Likewise, attempts to customize this face in Emacs built with GTK and | |
461a3118 | 491 | in the MS-Windows/Mac ports are ignored by the respective GUI toolkits; |
9e6bb19f EZ |
492 | you need to use system-wide styles and options to change the |
493 | appearance of the menus. | |
b8f3a9e3 GM |
494 | @end table |
495 | ||
b8f3a9e3 GM |
496 | @node Font Lock |
497 | @section Font Lock mode | |
498 | @cindex Font Lock mode | |
499 | @cindex mode, Font Lock | |
500 | @cindex syntax highlighting and coloring | |
501 | ||
8cc11660 | 502 | Font Lock mode is a minor mode, always local to a particular buffer, |
0015d677 | 503 | which highlights (or ``fontifies'') the buffer contents according to |
8cc11660 RS |
504 | the syntax of the text you are editing. It can recognize comments and |
505 | strings in most languages; in several languages, it can also recognize | |
506 | and properly highlight various other important constructs---for | |
507 | example, names of functions being defined or reserved keywords. | |
508 | Some special modes, such as Occur mode and Info mode, have completely | |
509 | specialized ways of assigning fonts for Font Lock mode. | |
b8f3a9e3 GM |
510 | |
511 | @findex font-lock-mode | |
c4e8acbc CY |
512 | Font Lock mode is turned on by default in all modes which support it. |
513 | You can toggle font-lock for each buffer with the command @kbd{M-x | |
514 | font-lock-mode}. Using a positive argument unconditionally turns Font | |
515 | Lock mode on, and a negative or zero argument turns it off. | |
b8f3a9e3 GM |
516 | |
517 | @findex global-font-lock-mode | |
518 | @vindex global-font-lock-mode | |
c4e8acbc CY |
519 | If you do not wish Font Lock mode to be turned on by default, |
520 | customize the variable @code{global-font-lock-mode} using the Customize | |
521 | interface (@pxref{Easy Customization}), or use the function | |
d239287a | 522 | @code{global-font-lock-mode} in your @file{.emacs} file, like this: |
b8f3a9e3 GM |
523 | |
524 | @example | |
c4e8acbc | 525 | (global-font-lock-mode 0) |
b8f3a9e3 GM |
526 | @end example |
527 | ||
43d67313 RS |
528 | @noindent |
529 | This variable, like all the variables that control Font Lock mode, | |
530 | take effect whenever fontification is done; that is, potentially at | |
531 | any time. | |
532 | ||
c4e8acbc | 533 | @findex turn-on-font-lock |
54952612 RS |
534 | If you have disabled Global Font Lock mode, you can still enable Font |
535 | Lock for specific major modes by adding the function | |
c4e8acbc CY |
536 | @code{turn-on-font-lock} to the mode hooks (@pxref{Hooks}). For |
537 | example, to enable Font Lock mode for editing C files, you can do this: | |
538 | ||
539 | @example | |
540 | (add-hook 'c-mode-hook 'turn-on-font-lock) | |
541 | @end example | |
0015d677 | 542 | |
b8f3a9e3 GM |
543 | Font Lock mode uses several specifically named faces to do its job, |
544 | including @code{font-lock-string-face}, @code{font-lock-comment-face}, | |
54952612 RS |
545 | and others. The easiest way to find them all is to use @kbd{M-x |
546 | customize-group @key{RET} font-lock-faces @key{RET}}. You can then | |
547 | use that customization buffer to customize the appearance of these | |
548 | faces. @xref{Face Customization}. | |
b8f3a9e3 | 549 | |
54952612 RS |
550 | You can also customize these faces using @kbd{M-x |
551 | set-face-foreground} or @kbd{M-x set-face-background}. @xref{Faces}. | |
b8f3a9e3 | 552 | |
b8f3a9e3 GM |
553 | @vindex font-lock-maximum-decoration |
554 | The variable @code{font-lock-maximum-decoration} specifies the | |
555 | preferred level of fontification, for modes that provide multiple | |
556 | levels. Level 1 is the least amount of fontification; some modes | |
557 | support levels as high as 3. The normal default is ``as high as | |
558 | possible.'' You can specify an integer, which applies to all modes, or | |
559 | you can specify different numbers for particular major modes; for | |
560 | example, to use level 1 for C/C++ modes, and the default level | |
561 | otherwise, use this: | |
562 | ||
563 | @example | |
564 | (setq font-lock-maximum-decoration | |
565 | '((c-mode . 1) (c++-mode . 1))) | |
566 | @end example | |
567 | ||
568 | @vindex font-lock-maximum-size | |
569 | Fontification can be too slow for large buffers, so you can suppress | |
54952612 RS |
570 | it for buffers above a certain size. The variable |
571 | @code{font-lock-maximum-size} specifies a buffer size, beyond which | |
572 | buffer fontification is suppressed. | |
b8f3a9e3 GM |
573 | |
574 | @c @w is used below to prevent a bad page-break. | |
575 | @vindex font-lock-beginning-of-syntax-function | |
e07e854d EZ |
576 | @cindex incorrect fontification |
577 | @cindex parenthesis in column zero and fontification | |
578 | @cindex brace in column zero and fontification | |
b8f3a9e3 GM |
579 | Comment and string fontification (or ``syntactic'' fontification) |
580 | relies on analysis of the syntactic structure of the buffer text. For | |
174862cf RS |
581 | the sake of speed, some modes, including Lisp mode, rely on a special |
582 | convention: an open-parenthesis or open-brace in the leftmost column | |
583 | always defines the @w{beginning} of a defun, and is thus always | |
584 | outside any string or comment. (@xref{Left Margin Paren}.) If you | |
585 | don't follow this convention, Font Lock mode can misfontify the text | |
586 | that follows an open-parenthesis or open-brace in the leftmost column | |
587 | that is inside a string or comment. | |
b8f3a9e3 | 588 | |
6bb2ed9b | 589 | @cindex slow display during scrolling |
b8f3a9e3 GM |
590 | The variable @code{font-lock-beginning-of-syntax-function} (always |
591 | buffer-local) specifies how Font Lock mode can find a position | |
592 | guaranteed to be outside any comment or string. In modes which use the | |
593 | leftmost column parenthesis convention, the default value of the variable | |
594 | is @code{beginning-of-defun}---that tells Font Lock mode to use the | |
595 | convention. If you set this variable to @code{nil}, Font Lock no longer | |
596 | relies on the convention. This avoids incorrect results, but the price | |
597 | is that, in some cases, fontification for a changed text must rescan | |
6bb2ed9b EZ |
598 | buffer text from the beginning of the buffer. This can considerably |
599 | slow down redisplay while scrolling, particularly if you are close to | |
600 | the end of a large buffer. | |
b8f3a9e3 GM |
601 | |
602 | @findex font-lock-add-keywords | |
603 | Font Lock highlighting patterns already exist for many modes, but you | |
604 | may want to fontify additional patterns. You can use the function | |
605 | @code{font-lock-add-keywords}, to add your own highlighting patterns for | |
606 | a particular mode. For example, to highlight @samp{FIXME:} words in C | |
607 | comments, use this: | |
608 | ||
609 | @example | |
610 | (font-lock-add-keywords | |
611 | 'c-mode | |
612 | '(("\\<\\(FIXME\\):" 1 font-lock-warning-face t))) | |
613 | @end example | |
614 | ||
4063fff3 EZ |
615 | @findex font-lock-remove-keywords |
616 | To remove keywords from the font-lock highlighting patterns, use the | |
cd77ce13 | 617 | function @code{font-lock-remove-keywords}. @xref{Search-based |
09139bc5 LT |
618 | Fontification,,, elisp, The Emacs Lisp Reference Manual}, for |
619 | documentation of the format of this list. | |
4063fff3 | 620 | |
3be9b0ca EZ |
621 | @cindex just-in-time (JIT) font-lock |
622 | @cindex background syntax highlighting | |
623 | Fontifying large buffers can take a long time. To avoid large | |
624 | delays when a file is visited, Emacs fontifies only the visible | |
625 | portion of a buffer. As you scroll through the buffer, each portion | |
626 | that becomes visible is fontified as soon as it is displayed. The | |
627 | parts of the buffer that are not displayed are fontified | |
de4a4c41 | 628 | ``stealthily,'' in the background, i.e.@: when Emacs is idle. You can |
bdc3b3be RS |
629 | control this background fontification, also called @dfn{Just-In-Time} |
630 | (or @dfn{JIT}) Lock, by customizing variables in the customization | |
631 | group @samp{jit-lock}. @xref{Specific Customization}. | |
3be9b0ca | 632 | |
b8f3a9e3 | 633 | @node Highlight Interactively |
54952612 | 634 | @section Interactive Highlighting |
b8f3a9e3 GM |
635 | @cindex highlighting by matching |
636 | @cindex interactive highlighting | |
54952612 | 637 | @cindex Highlight Changes mode |
b8f3a9e3 | 638 | |
54952612 RS |
639 | @findex highlight-changes-mode |
640 | Use @kbd{M-x highlight-changes-mode} to enable (or disable) | |
641 | Highlight Changes mode, a minor mode that uses faces (colors, | |
642 | typically) to indicate which parts of the buffer were changed most | |
643 | recently. | |
b8f3a9e3 | 644 | |
54952612 | 645 | @cindex Hi Lock mode |
b8f3a9e3 | 646 | @findex hi-lock-mode |
54952612 RS |
647 | Hi Lock mode is another minor mode, which highlights text that |
648 | matches your specified regular expressions. For example, you might | |
649 | wish to see all the references to a certain variable in a program | |
650 | source file, highlight certain parts in a voluminous output of some | |
651 | program, or make certain names stand out in an article. Use the | |
652 | @kbd{M-x hi-lock-mode} command to enable (or disable) Hi Lock mode. | |
653 | To enable Hi Lock mode for all buffers, use @kbd{M-x | |
654 | global-hi-lock-mode} or place @code{(global-hi-lock-mode 1)} in your | |
655 | @file{.emacs} file. | |
656 | ||
657 | Hi Lock mode works like Font Lock mode (@pxref{Font Lock}), except | |
658 | that you specify explicitly the regular expressions to highlight. You | |
659 | control them with these commands: | |
b8f3a9e3 GM |
660 | |
661 | @table @kbd | |
662 | @item C-x w h @var{regexp} @key{RET} @var{face} @key{RET} | |
663 | @kindex C-x w h | |
664 | @findex highlight-regexp | |
cedf175b | 665 | Highlight text that matches @var{regexp} using face @var{face} |
54952612 RS |
666 | (@code{highlight-regexp}). The highlighting will remain as long as |
667 | the buffer is loaded. For example, to highlight all occurrences of | |
668 | the word ``whim'' using the default face (a yellow background) | |
669 | @kbd{C-x w h whim @key{RET} @key{RET}}. Any face can be used for | |
670 | highlighting, Hi Lock provides several of its own and these are | |
671 | pre-loaded into a history list. While being prompted for a face use | |
672 | @kbd{M-p} and @kbd{M-n} to cycle through them. | |
673 | ||
674 | You can use this command multiple times, specifying various regular | |
675 | expressions to highlight in different ways. | |
b8f3a9e3 GM |
676 | |
677 | @item C-x w r @var{regexp} @key{RET} | |
678 | @kindex C-x w r | |
679 | @findex unhighlight-regexp | |
630acdcc | 680 | Unhighlight @var{regexp} (@code{unhighlight-regexp}). |
54952612 RS |
681 | |
682 | If you invoke this from the menu, you select the expression to | |
683 | unhighlight from a list. If you invoke this from the keyboard, you | |
684 | use the minibuffer. It will show the most recently added regular | |
685 | expression; use @kbd{M-p} to show the next older expression and | |
686 | @kbd{M-n} to select the next newer expression. (You can also type the | |
687 | expression by hand, with completion.) When the expression you want to | |
688 | unhighlight appears in the minibuffer, press @kbd{@key{RET}} to exit | |
689 | the minibuffer and unhighlight it. | |
b8f3a9e3 GM |
690 | |
691 | @item C-x w l @var{regexp} @key{RET} @var{face} @key{RET} | |
692 | @kindex C-x w l | |
693 | @findex highlight-lines-matching-regexp | |
694 | @cindex lines, highlighting | |
695 | @cindex highlighting lines of text | |
04d0b662 | 696 | Highlight entire lines containing a match for @var{regexp}, using face |
b8f3a9e3 GM |
697 | @var{face} (@code{highlight-lines-matching-regexp}). |
698 | ||
699 | @item C-x w b | |
700 | @kindex C-x w b | |
701 | @findex hi-lock-write-interactive-patterns | |
702 | Insert all the current highlighting regexp/face pairs into the buffer | |
703 | at point, with comment delimiters to prevent them from changing your | |
54952612 RS |
704 | program. (This key binding runs the |
705 | @code{hi-lock-write-interactive-patterns} command.) | |
b8f3a9e3 GM |
706 | |
707 | These patterns will be read the next time you visit the file while | |
cedf175b | 708 | Hi Lock mode is enabled, or whenever you use the @kbd{M-x |
b8f3a9e3 GM |
709 | hi-lock-find-patterns} command. |
710 | ||
711 | @item C-x w i | |
712 | @kindex C-x w i | |
713 | @findex hi-lock-find-patterns | |
714 | @vindex hi-lock-exclude-modes | |
715 | Re-read regexp/face pairs in the current buffer | |
630acdcc | 716 | (@code{hi-lock-write-interactive-patterns}). Users familiar with Font |
cedf175b EZ |
717 | Lock keywords might interactively enter patterns |
718 | (@code{highlight-regexp}), write them into the file | |
719 | (@code{hi-lock-write-interactive-patterns}), edit them, perhaps | |
720 | including different faces for different parenthesized parts of the | |
721 | match, and finally use this command | |
722 | (@code{hi-lock-write-interactive-patterns}) to have Hi Lock highlight | |
723 | them. | |
b8f3a9e3 | 724 | |
43d67313 RS |
725 | This command does nothing if the current major mode's symbol is a member |
726 | of the list @code{hi-lock-exclude-modes}. | |
b8f3a9e3 GM |
727 | @end table |
728 | ||
fad78d58 RS |
729 | @node Fringes |
730 | @section Window Fringes | |
731 | @cindex fringes | |
732 | ||
733 | On a graphical display, each Emacs window normally has narrow | |
734 | @dfn{fringes} on the left and right edges. The fringes display | |
735 | indications about the text in the window. | |
736 | ||
737 | The most common use of the fringes is to indicate a continuation | |
738 | line, when one line of text is split into multiple lines on the | |
739 | screen. The left fringe shows a curving arrow for each screen line | |
740 | except the first, indicating that ``this is not the real beginning.'' | |
741 | The right fringe shows a curving arrow for each screen line except the | |
742 | last, indicating that ``this is not the real end.'' | |
743 | ||
566da2e7 | 744 | The fringes indicate line truncation with short horizontal arrows |
fad78d58 | 745 | meaning ``there's more text on this line which is scrolled |
566da2e7 EZ |
746 | horizontally out of view;'' clicking the mouse on one of the arrows |
747 | scrolls the display horizontally in the direction of the arrow. The | |
d239287a | 748 | fringes can also indicate other things, such as empty lines, or where a |
566da2e7 | 749 | program you are debugging is executing (@pxref{Debuggers}). |
fad78d58 RS |
750 | |
751 | @findex set-fringe-style | |
752 | @findex fringe-mode | |
753 | You can enable and disable the fringes for all frames using | |
754 | @kbd{M-x fringe-mode}. To enable and disable the fringes | |
755 | for the selected frame, use @kbd{M-x set-fringe-style}. | |
756 | ||
9d2908a6 RS |
757 | @node Displaying Boundaries |
758 | @section Displaying Boundaries | |
759 | ||
760 | @vindex indicate-buffer-boundaries | |
761 | On a graphical display, Emacs can indicate the buffer boundaries in | |
762 | the fringes. It indicates the first line and the last line with | |
763 | angle images in the fringes. This can be combined with up and down | |
764 | arrow images which say whether it is possible to scroll the window up | |
765 | and down. | |
766 | ||
767 | The buffer-local variable @code{indicate-buffer-boundaries} controls | |
768 | how the buffer boundaries and window scrolling is indicated in the | |
769 | fringes. If the value is @code{left} or @code{right}, both angle and | |
770 | arrow bitmaps are displayed in the left or right fringe, respectively. | |
771 | ||
772 | If value is an alist, each element @code{(@var{indicator} . | |
773 | @var{position})} specifies the position of one of the indicators. | |
774 | The @var{indicator} must be one of @code{top}, @code{bottom}, | |
775 | @code{up}, @code{down}, or @code{t} which specifies the default | |
776 | position for the indicators not present in the alist. | |
777 | The @var{position} is one of @code{left}, @code{right}, or @code{nil} | |
778 | which specifies not to show this indicator. | |
779 | ||
780 | For example, @code{((top . left) (t . right))} places the top angle | |
781 | bitmap in left fringe, the bottom angle bitmap in right fringe, and | |
782 | both arrow bitmaps in right fringe. To show just the angle bitmaps in | |
783 | the left fringe, but no arrow bitmaps, use @code{((top . left) | |
784 | (bottom . left))}. | |
785 | ||
786 | @vindex default-indicate-buffer-boundaries | |
787 | The value of the variable @code{default-indicate-buffer-boundaries} | |
788 | is the default value for @code{indicate-buffer-boundaries} in buffers | |
789 | that do not override it. | |
790 | ||
fad78d58 RS |
791 | @node Useless Whitespace |
792 | @section Useless Whitespace | |
793 | ||
794 | @cindex trailing whitespace | |
795 | @cindex whitespace, trailing | |
796 | @vindex show-trailing-whitespace | |
797 | It is easy to leave unnecessary spaces at the end of a line, or | |
798 | empty lines at the end of a file, without realizing it. In most | |
799 | cases, this @dfn{trailing whitespace} has no effect, but there are | |
54952612 RS |
800 | special circumstances where it matters. It can also be a nuisance |
801 | that the line has ``changed,'' when the change is just spaces added or | |
802 | removed at the end. | |
fad78d58 RS |
803 | |
804 | You can make trailing whitespace at the end of a line visible on the | |
805 | screen by setting the buffer-local variable | |
806 | @code{show-trailing-whitespace} to @code{t}. Then Emacs displays | |
807 | trailing whitespace in the face @code{trailing-whitespace}. | |
808 | ||
809 | This feature does not apply when point is at the end of the line | |
810 | containing the whitespace. Strictly speaking, that is ``trailing | |
811 | whitespace'' nonetheless, but displaying it specially in that case | |
812 | looks ugly while you are typing in new text. In this special case, | |
813 | the location of point is enough to show you that the spaces are | |
814 | present. | |
815 | ||
816 | @findex delete-trailing-whitespace | |
817 | To delete all trailing whitespace within the current buffer's | |
818 | accessible portion (@pxref{Narrowing}), type @kbd{M-x | |
819 | delete-trailing-whitespace @key{RET}}. (This command does not remove | |
820 | the form-feed characters.) | |
821 | ||
23e3383d | 822 | @vindex indicate-empty-lines |
fad78d58 | 823 | @vindex default-indicate-empty-lines |
877db12e RS |
824 | @cindex unused lines |
825 | @cindex fringes, and unused line indication | |
826 | Emacs can indicate unused lines at the end of the window with a | |
827 | small image in the left fringe (@pxref{Fringes}). The image appears | |
828 | for window lines that do not correspond to any buffer text. Blank | |
829 | lines at the end of the buffer then stand out because they do not have | |
830 | this image in the fringe. | |
831 | ||
832 | To enable this feature, set the buffer-local variable | |
23e3383d | 833 | @code{indicate-empty-lines} to a non-@code{nil} value. The default |
877db12e | 834 | value of this variable is controlled by the variable |
23e3383d | 835 | @code{default-indicate-empty-lines}; by setting that variable, you |
877db12e | 836 | can enable or disable this feature for all new buffers. (This feature |
54952612 | 837 | currently doesn't work on text-only terminals.) |
fad78d58 | 838 | |
6bf7aab6 DL |
839 | @node Selective Display |
840 | @section Selective Display | |
4946337d | 841 | @cindex selective display |
6bf7aab6 DL |
842 | @findex set-selective-display |
843 | @kindex C-x $ | |
844 | ||
845 | Emacs has the ability to hide lines indented more than a certain number | |
846 | of columns (you specify how many columns). You can use this to get an | |
847 | overview of a part of a program. | |
848 | ||
d239287a LT |
849 | To hide lines in the current buffer, type @kbd{C-x $} |
850 | (@code{set-selective-display}) with a numeric argument @var{n}. Then | |
851 | lines with at least @var{n} columns of indentation disappear from the | |
852 | screen. The only indication of their presence is that three dots | |
853 | (@samp{@dots{}}) appear at the end of each visible line that is | |
854 | followed by one or more hidden ones. | |
6bf7aab6 DL |
855 | |
856 | The commands @kbd{C-n} and @kbd{C-p} move across the hidden lines as | |
857 | if they were not there. | |
858 | ||
859 | The hidden lines are still present in the buffer, and most editing | |
860 | commands see them as usual, so you may find point in the middle of the | |
861 | hidden text. When this happens, the cursor appears at the end of the | |
862 | previous line, after the three dots. If point is at the end of the | |
863 | visible line, before the newline that ends it, the cursor appears before | |
864 | the three dots. | |
865 | ||
866 | To make all lines visible again, type @kbd{C-x $} with no argument. | |
867 | ||
868 | @vindex selective-display-ellipses | |
869 | If you set the variable @code{selective-display-ellipses} to | |
870 | @code{nil}, the three dots do not appear at the end of a line that | |
871 | precedes hidden lines. Then there is no visible indication of the | |
872 | hidden lines. This variable becomes local automatically when set. | |
873 | ||
0015d677 RS |
874 | See also @ref{Outline Mode} for another way to hide part of |
875 | the text in a buffer. | |
876 | ||
6bf7aab6 DL |
877 | @node Optional Mode Line |
878 | @section Optional Mode Line Features | |
879 | ||
b213b767 LK |
880 | @cindex buffer size display |
881 | @cindex display of buffer size | |
882 | @findex size-indication-mode | |
883 | The buffer percentage @var{pos} indicates the percentage of the | |
884 | buffer above the top of the window. You can additionally display the | |
885 | size of the buffer by typing @kbd{M-x size-indication-mode} to turn on | |
886 | Size Indication mode. The size will be displayed immediately | |
887 | following the buffer percentage like this: | |
888 | ||
889 | @example | |
890 | @var{POS} of @var{SIZE} | |
891 | @end example | |
892 | ||
893 | @noindent | |
894 | Here @var{SIZE} is the human readable representation of the number of | |
895 | characters in the buffer, which means that @samp{k} for 10^3, @samp{M} | |
896 | for 10^6, @samp{G} for 10^9, etc., are used to abbreviate. | |
897 | ||
898 | @cindex narrowing, and buffer size display | |
899 | If you have narrowed the buffer (@pxref{Narrowing}), the size of the | |
900 | accessible part of the buffer is shown. | |
901 | ||
e598186c RS |
902 | @cindex line number display |
903 | @cindex display of line number | |
6bf7aab6 DL |
904 | @findex line-number-mode |
905 | The current line number of point appears in the mode line when Line | |
906 | Number mode is enabled. Use the command @kbd{M-x line-number-mode} to | |
907 | turn this mode on and off; normally it is on. The line number appears | |
b213b767 | 908 | after the buffer percentage @var{pos}, with the letter @samp{L} to |
6bf7aab6 DL |
909 | indicate what it is. @xref{Minor Modes}, for more information about |
910 | minor modes and about how to use this command. | |
911 | ||
43f971ab EZ |
912 | @cindex narrowing, and line number display |
913 | If you have narrowed the buffer (@pxref{Narrowing}), the displayed | |
914 | line number is relative to the accessible portion of the buffer. | |
54952612 RS |
915 | Thus, it isn't suitable as an argument to @code{goto-line}. (Use |
916 | @code{what-line} command to see the line number relative to the whole | |
917 | file.) | |
43f971ab | 918 | |
6bf7aab6 DL |
919 | @vindex line-number-display-limit |
920 | If the buffer is very large (larger than the value of | |
921 | @code{line-number-display-limit}), then the line number doesn't appear. | |
922 | Emacs doesn't compute the line number when the buffer is large, because | |
43f971ab EZ |
923 | that would be too slow. Set it to @code{nil} to remove the limit. |
924 | ||
925 | @vindex line-number-display-limit-width | |
926 | Line-number computation can also be slow if the lines in the buffer | |
927 | are too long. For this reason, Emacs normally doesn't display line | |
928 | numbers if the average width, in characters, of lines near point is | |
929 | larger than the value of the variable | |
930 | @code{line-number-display-limit-width}. The default value is 200 | |
931 | characters. | |
6bf7aab6 DL |
932 | |
933 | @cindex Column Number mode | |
934 | @cindex mode, Column Number | |
935 | @findex column-number-mode | |
936 | You can also display the current column number by turning on Column | |
937 | Number mode. It displays the current column number preceded by the | |
938 | letter @samp{C}. Type @kbd{M-x column-number-mode} to toggle this mode. | |
939 | ||
940 | @findex display-time | |
941 | @cindex time (on mode line) | |
942 | Emacs can optionally display the time and system load in all mode | |
4f00b8c1 DL |
943 | lines. To enable this feature, type @kbd{M-x display-time} or customize |
944 | the option @code{display-time-mode}. The information added to the mode | |
945 | line usually appears after the buffer name, before the mode names and | |
946 | their parentheses. It looks like this: | |
6bf7aab6 DL |
947 | |
948 | @example | |
949 | @var{hh}:@var{mm}pm @var{l.ll} | |
950 | @end example | |
951 | ||
952 | @noindent | |
953 | @vindex display-time-24hr-format | |
954 | Here @var{hh} and @var{mm} are the hour and minute, followed always by | |
955 | @samp{am} or @samp{pm}. @var{l.ll} is the average number of running | |
956 | processes in the whole system recently. (Some fields may be missing if | |
957 | your operating system cannot support them.) If you prefer time display | |
958 | in 24-hour format, set the variable @code{display-time-24hr-format} | |
959 | to @code{t}. | |
960 | ||
961 | @cindex mail (on mode line) | |
72bd7b7b DL |
962 | @vindex display-time-use-mail-icon |
963 | @vindex display-time-mail-face | |
fad78d58 RS |
964 | @vindex display-time-mail-file |
965 | @vindex display-time-mail-directory | |
6bf7aab6 | 966 | The word @samp{Mail} appears after the load level if there is mail |
72bd7b7b DL |
967 | for you that you have not read yet. On a graphical display you can use |
968 | an icon instead of @samp{Mail} by customizing | |
969 | @code{display-time-use-mail-icon}; this may save some space on the mode | |
970 | line. You can customize @code{display-time-mail-face} to make the mail | |
fad78d58 RS |
971 | indicator prominent. Use @code{display-time-mail-file} to specify |
972 | the mail file to check, or set @code{display-time-mail-directory} | |
973 | to specify the directory to check for incoming mail (any nonempty regular | |
974 | file in the directory is considered as ``newly arrived mail''). | |
6bf7aab6 | 975 | |
47d7776c | 976 | @cindex mode line, 3D appearance |
bd3ead08 EZ |
977 | @cindex attributes of mode line, changing |
978 | @cindex non-integral number of lines in a window | |
04d0b662 RS |
979 | By default, the mode line is drawn on graphics displays with |
980 | 3D-style highlighting, like that of a button when it is not being | |
981 | pressed. If you don't like this effect, you can disable the 3D | |
982 | highlighting of the mode line, by customizing the attributes of the | |
54952612 | 983 | @code{mode-line} face. @xref{Face Customization}. |
bd3ead08 | 984 | |
b9e58bf2 | 985 | @cindex non-selected windows, mode line appearance |
ac6875fc | 986 | By default, the mode line of nonselected windows is displayed in a |
1c9f5f23 | 987 | different face, called @code{mode-line-inactive}. Only the selected |
ac6875fc RS |
988 | window is displayed in the @code{mode-line} face. This helps show |
989 | which window is selected. When the minibuffer is selected, since | |
990 | it has no mode line, the window from which you activated the minibuffer | |
991 | has its mode line displayed using @code{mode-line}; as a result, | |
992 | ordinary entry to the minibuffer does not change any mode lines. | |
993 | ||
994 | @vindex mode-line-in-non-selected-windows | |
995 | You can disable use of @code{mode-line-inactive} by setting variable | |
1c9f5f23 KS |
996 | @code{mode-line-in-non-selected-windows} to @code{nil}; then all mode |
997 | lines are displayed in the @code{mode-line} face. | |
b9e58bf2 | 998 | |
589a3f9f RS |
999 | @vindex eol-mnemonic-unix |
1000 | @vindex eol-mnemonic-dos | |
1001 | @vindex eol-mnemonic-mac | |
1002 | @vindex eol-mnemonic-undecided | |
1003 | You can customize the mode line display for each of the end-of-line | |
1004 | formats by setting each of the variables @code{eol-mnemonic-unix}, | |
1005 | @code{eol-mnemonic-dos}, @code{eol-mnemonic-mac}, and | |
54952612 | 1006 | @code{eol-mnemonic-undecided} to the strings you prefer. |
589a3f9f | 1007 | |
6bf7aab6 DL |
1008 | @node Text Display |
1009 | @section How Text Is Displayed | |
1010 | @cindex characters (in text) | |
1011 | ||
76dd3692 | 1012 | @acronym{ASCII} printing characters (octal codes 040 through 0176) in Emacs |
13b9ee95 | 1013 | buffers are displayed with their graphics, as are non-ASCII multibyte |
6bf7aab6 DL |
1014 | printing characters (octal codes above 0400). |
1015 | ||
76dd3692 | 1016 | Some @acronym{ASCII} control characters are displayed in special ways. The |
6bf7aab6 DL |
1017 | newline character (octal code 012) is displayed by starting a new line. |
1018 | The tab character (octal code 011) is displayed by moving to the next | |
1019 | tab stop column (normally every 8 columns). | |
1020 | ||
76dd3692 | 1021 | Other @acronym{ASCII} control characters are normally displayed as a caret |
6bf7aab6 | 1022 | (@samp{^}) followed by the non-control version of the character; thus, |
54952612 RS |
1023 | control-A is displayed as @samp{^A}. The caret appears in face |
1024 | @code{escape-glyph}. | |
1025 | ||
1026 | Non-@acronym{ASCII} characters 0200 through 0237 (octal) are | |
1027 | displayed with octal escape sequences; thus, character code 0230 | |
1028 | (octal) is displayed as @samp{\230}. The backslash appears in face | |
1029 | @code{escape-glyph}. | |
1030 | ||
1031 | @vindex ctl-arrow | |
1032 | If the variable @code{ctl-arrow} is @code{nil}, control characters in | |
1033 | the buffer are displayed with octal escape sequences, except for newline | |
1034 | and tab. Altering the value of @code{ctl-arrow} makes it local to the | |
1035 | current buffer; until that time, the default value is in effect. The | |
1036 | default is initially @code{t}. | |
1037 | ||
1038 | The display of character codes 0240 through 0377 (octal) may be | |
1039 | either as escape sequences or as graphics. They do not normally occur | |
1040 | in multibyte buffers, but if they do, they are displayed as Latin-1 | |
1041 | graphics. In unibyte mode, if you enable European display they are | |
1042 | displayed using their graphics (assuming your terminal supports them), | |
662286c3 | 1043 | otherwise as escape sequences. @xref{Unibyte Mode}. |
6bf7aab6 | 1044 | |
470a11a3 | 1045 | @vindex nobreak-char-display |
367aa52c RS |
1046 | @cindex no-break space, display |
1047 | @cindex no-break hyphen, display | |
1048 | @cindex soft hyphen, display | |
470a11a3 RS |
1049 | Some character sets define ``no-break'' versions of the space and |
1050 | hyphen characters, which are used where a line should not be broken. | |
1051 | Emacs normally displays these characters with special faces | |
1052 | (respectively, @code{nobreak-space} and @code{escape-glyph}) to | |
1053 | distinguish them from ordinary spaces and hyphens. You can turn off | |
1054 | this feature by setting the variable @code{nobreak-char-display} to | |
1055 | @code{nil}. If you set the variable to any other value, that means to | |
1056 | prefix these characters with an escape character. | |
b5cced4b | 1057 | |
54952612 RS |
1058 | @vindex tab-width |
1059 | @vindex default-tab-width | |
1060 | Normally, a tab character in the buffer is displayed as whitespace which | |
1061 | extends to the next display tab stop position, and display tab stops come | |
1062 | at intervals equal to eight spaces. The number of spaces per tab is | |
1063 | controlled by the variable @code{tab-width}, which is made local by | |
1064 | changing it. Note that how the tab character | |
1065 | in the buffer is displayed has nothing to do with the definition of | |
1066 | @key{TAB} as a command. The variable @code{tab-width} must have an | |
1067 | integer value between 1 and 1000, inclusive. The variable | |
1068 | @code{default-tab-width} controls the default value of this variable | |
1069 | for buffers where you have not set it locally. | |
1070 | ||
1071 | You can customize the way any particular character code is displayed | |
1072 | by means of a display table. @xref{Display Tables,, Display Tables, | |
1073 | elisp, The Emacs Lisp Reference Manual}. | |
1074 | ||
0015d677 RS |
1075 | @node Cursor Display |
1076 | @section Displaying the Cursor | |
1077 | ||
1078 | @findex blink-cursor-mode | |
1079 | @vindex blink-cursor-alist | |
1080 | @cindex cursor, locating visually | |
1081 | @cindex cursor, blinking | |
1082 | You can customize the cursor's color, and whether it blinks, using | |
1083 | the @code{cursor} Custom group (@pxref{Easy Customization}). On | |
098199b1 | 1084 | a graphical display, the command @kbd{M-x blink-cursor-mode} enables |
0015d677 RS |
1085 | or disables the blinking of the cursor. (On text terminals, the |
1086 | terminal itself blinks the cursor, and Emacs has no control over it.) | |
1087 | You can control how the cursor appears when it blinks off by setting | |
1088 | the variable @code{blink-cursor-alist}. | |
1089 | ||
468160b7 SM |
1090 | @vindex visible-cursor |
1091 | Some text terminals offer two different cursors: the normal cursor | |
1092 | and the very visible cursor, where the latter may be e.g. bigger or | |
43d67313 RS |
1093 | blinking. By default Emacs uses the very visible cursor, and switches |
1094 | to it when you start or resume Emacs. If the variable | |
1095 | @code{visible-cursor} is @code{nil} when Emacs starts or resumes, it | |
1096 | doesn't switch, so it uses the normal cursor. | |
468160b7 | 1097 | |
0015d677 RS |
1098 | @cindex cursor in non-selected windows |
1099 | @vindex cursor-in-non-selected-windows | |
1100 | Normally, the cursor appears in non-selected windows in the ``off'' | |
1101 | state, with the same appearance as when the blinking cursor blinks | |
5a7f4c1b | 1102 | ``off.'' For a box cursor, this is a hollow box; for a bar cursor, |
0015d677 RS |
1103 | this is a thinner bar. To turn off cursors in non-selected windows, |
1104 | customize the variable @code{cursor-in-non-selected-windows} and assign | |
1105 | it a @code{nil} value. | |
1106 | ||
1107 | @vindex x-stretch-cursor | |
1108 | @cindex wide block cursor | |
098199b1 | 1109 | On graphical displays, Emacs can optionally draw the block cursor |
0015d677 RS |
1110 | as wide as the character under the cursor---for example, if the cursor |
1111 | is on a tab character, it would cover the full width occupied by that | |
1112 | tab character. To enable this feature, set the variable | |
1113 | @code{x-stretch-cursor} to a non-@code{nil} value. | |
1114 | ||
1115 | @findex hl-line-mode | |
1116 | @findex global-hl-line-mode | |
1117 | @cindex highlight current line | |
54952612 RS |
1118 | To make the cursor even more visible, you can use HL Line mode, a |
1119 | minor mode that highlights the line containing point. Use @kbd{M-x | |
0015d677 RS |
1120 | hl-line-mode} to enable or disable it in the current buffer. @kbd{M-x |
1121 | global-hl-line-mode} enables or disables the same mode globally. | |
1122 | ||
9d2908a6 RS |
1123 | @node Line Truncation |
1124 | @section Truncation of Lines | |
0015d677 RS |
1125 | |
1126 | @cindex truncation | |
1127 | @cindex line truncation, and fringes | |
1128 | As an alternative to continuation, Emacs can display long lines by | |
1129 | @dfn{truncation}. This means that all the characters that do not fit | |
1130 | in the width of the screen or window do not appear at all. On | |
54952612 RS |
1131 | graphical displays, a small straight arrow in the fringe indicates |
1132 | truncation at either end of the line. On text-only terminals, @samp{$} | |
0015d677 RS |
1133 | appears in the first column when there is text truncated to the left, |
1134 | and in the last column when there is text truncated to the right. | |
1135 | ||
1136 | @vindex truncate-lines | |
1137 | @findex toggle-truncate-lines | |
1138 | Horizontal scrolling automatically causes line truncation | |
1139 | (@pxref{Horizontal Scrolling}). You can explicitly enable line | |
1140 | truncation for a particular buffer with the command @kbd{M-x | |
1141 | toggle-truncate-lines}. This works by locally changing the variable | |
1142 | @code{truncate-lines}. If that variable is non-@code{nil}, long lines | |
1143 | are truncated; if it is @code{nil}, they are continued onto multiple | |
1144 | screen lines. Setting the variable @code{truncate-lines} in any way | |
1145 | makes it local to the current buffer; until that time, the default | |
1146 | value is in effect. The default value is normally @code{nil}. | |
6bf7aab6 DL |
1147 | |
1148 | @c @vindex truncate-partial-width-windows @c Idx entry is in Split Windows. | |
1149 | If the variable @code{truncate-partial-width-windows} is | |
1150 | non-@code{nil}, it forces truncation rather than continuation in any | |
1151 | window less than the full width of the screen or frame, regardless of | |
1152 | the value of @code{truncate-lines}. For information about side-by-side | |
1153 | windows, see @ref{Split Window}. See also @ref{Display,, Display, | |
1154 | elisp, The Emacs Lisp Reference Manual}. | |
1155 | ||
80174a97 KS |
1156 | @vindex overflow-newline-into-fringe |
1157 | If the variable @code{overflow-newline-into-fringe} is | |
54952612 RS |
1158 | non-@code{nil} on a graphical display, then Emacs does not continue or |
1159 | truncate a line which is exactly as wide as the window. Instead, the | |
1160 | newline overflows into the right fringe, and the cursor appears in the | |
1161 | fringe when positioned on that newline. | |
80174a97 | 1162 | |
9d2908a6 RS |
1163 | @node Display Custom |
1164 | @section Customization of Display | |
80174a97 | 1165 | |
9d2908a6 RS |
1166 | This section describes variables (@pxref{Variables}) that you can |
1167 | change to customize how Emacs displays. Beginning users can skip | |
1168 | it. | |
1169 | @c the reason for that pxref is because an xref early in the | |
1170 | @c ``echo area'' section leads here. | |
62ea61af | 1171 | |
9d2908a6 RS |
1172 | @vindex inverse-video |
1173 | If the variable @code{inverse-video} is non-@code{nil}, Emacs attempts | |
1174 | to invert all the lines of the display from what they normally are. | |
62ea61af | 1175 | |
9d2908a6 RS |
1176 | @vindex visible-bell |
1177 | If the variable @code{visible-bell} is non-@code{nil}, Emacs attempts | |
1178 | to make the whole screen blink when it would normally make an audible bell | |
1179 | sound. This variable has no effect if your terminal does not have a way | |
1180 | to make the screen blink. | |
80174a97 | 1181 | |
9d2908a6 RS |
1182 | @vindex echo-keystrokes |
1183 | The variable @code{echo-keystrokes} controls the echoing of multi-character | |
1184 | keys; its value is the number of seconds of pause required to cause echoing | |
1185 | to start, or zero, meaning don't echo at all. The value takes effect when | |
1186 | there is someting to echo. @xref{Echo Area}. | |
80174a97 | 1187 | |
6bf7aab6 | 1188 | @vindex baud-rate |
54952612 RS |
1189 | The variable @anchor{baud-rate}@code{baud-rate} holds the output |
1190 | speed of the terminal, as far as Emacs knows. Setting this variable | |
1191 | does not change the speed of actual data transmission, but the value | |
1192 | is used for calculations. On text-only terminals, it affects padding, | |
1193 | and decisions about whether to scroll part of the screen or redraw it | |
1194 | instead. It also affects the behavior of incremental search. | |
1195 | ||
1196 | On graphical displays, @code{baud-rate} is only used to determine | |
1197 | how frequently to look for pending input during display updating. A | |
e598186c RS |
1198 | higher value of @code{baud-rate} means that check for pending input |
1199 | will be done less frequently. | |
6bf7aab6 | 1200 | |
62095f01 GM |
1201 | @cindex hourglass pointer display |
1202 | @vindex hourglass-delay | |
54952612 | 1203 | On graphical display, Emacs can optionally display the mouse pointer |
099bfef9 RS |
1204 | in a special shape to say that Emacs is busy. To turn this feature on |
1205 | or off, customize the group @code{cursor}. You can also control the | |
1206 | amount of time Emacs must remain busy before the busy indicator is | |
62095f01 | 1207 | displayed, by setting the variable @code{hourglass-delay}. |
099bfef9 | 1208 | |
9d2908a6 RS |
1209 | @vindex overline-margin |
1210 | On graphical display, this variables specifies the vertical position | |
1211 | of an overline above the text, including the height of the overline | |
1212 | itself (1 pixel). The default value is 2 pixels. | |
1213 | ||
1214 | @vindex x-underline-at-descent-line | |
1215 | On graphical display, Emacs normally draws an underline at the | |
1216 | baseline level of the font. If @code{x-underline-at-descent-line} is | |
1217 | non-@code{nil}, Emacs draws the underline at the same height as the | |
1218 | font's descent line. | |
1219 | ||
a66b12be RS |
1220 | @findex tty-suppress-bold-inverse-default-colors |
1221 | On some text-only terminals, bold face and inverse video together | |
1222 | result in text that is hard to read. Call the function | |
1223 | @code{tty-suppress-bold-inverse-default-colors} with a non-@code{nil} | |
1224 | argument to suppress the effect of bold-face in this case. | |
1225 | ||
54952612 RS |
1226 | @vindex no-redraw-on-reenter |
1227 | On a text-only terminal, when you reenter Emacs after suspending, Emacs | |
1228 | normally clears the screen and redraws the entire display. On some | |
1229 | terminals with more than one page of memory, it is possible to arrange | |
1230 | the termcap entry so that the @samp{ti} and @samp{te} strings (output | |
1231 | to the terminal when Emacs is entered and exited, respectively) switch | |
1232 | between pages of memory so as to use one page for Emacs and another | |
43d67313 | 1233 | page for other output. On such terminals, you might want to set the variable |
54952612 RS |
1234 | @code{no-redraw-on-reenter} non-@code{nil}; this tells Emacs to |
1235 | assume, when resumed, that the screen page it is using still contains | |
1236 | what Emacs last wrote there. | |
1237 | ||
ab5796a9 MB |
1238 | @ignore |
1239 | arch-tag: 2219f910-2ff0-4521-b059-1bd231a536c4 | |
1240 | @end ignore |